During the past years, the need for organic or thin film transistors (TFT) in industry for use in manufacturing screens of mobile phones, computer and television has increased. Moreover, there is a request for providing TFT on flexible substrates, hence, the replacement of glass by more flexible compounds as substrates. Thus, flexible electronics is a rapidly emerging area with possible applications in displays, sensors, medical electronics, identification tags, etc. Organic TFTs, etc. A variety of flexible substrates including metal foil, thin glass, polyimide (PE) and polyethylene naphthalate (PEN) have been utilized to realize flexible electronics. Even though organic TFTs are one of the best candidates due to their flexibility, there is still a need for promising material of high yield, reasonable mobility, and reliability. Furthermore, process temperature issues need to be overcome, since most flexible material substrates require low temperature processes, while the transistor materials require processes at higher temperatures.
Today, several examples for TFT on flexible materials exist. The gate insulator on an oxide TFT on glass is a plasma-enhanced chemical vapour deposition (PECVD) silicon nitride or silicon oxide thin film. For IGZO oxide TFT on flexible substrate, methyl siloxane as a gate dielectric has been used to fabricate an IGZO oxide TFT on paper (Nackbong Choi, Sharhukh A. Khan, Xiaoxiao Ma, Miltiadis Hatalis, 2011). Methyl siloxane has the advantage over strictly PECVD silicon nitride or silicon oxide as they have high resistance to breakage. A P-type ZnO may be obtained by a donor-acceptor co-doping method (T. Yamamoto and H. Katayama-Yoshida, 1999) (Yamamoto, 2002), by increasing the N concentration with group-Ill elements. A P-type IGZO was obtained by co-sputtering IGZO with 7% AlN target with an RF power of 60 W, sputtering pressure of 2×10-2 Toff and 0.6% 02 atmosphere. A rectifying diode device was realized by combining a n-type IGZO and p-type IGZO. (Kenkochiro Kobayashi, Yoshiumi Kohno, Yasumasa Tomita, Yasuhisa Maeda and Shigenori Matsushima, 2011) Printed and spin coated P3HT based TFT have been fabricated on polycarbonate film (Sung Kyu Park, Yong Hoon Kim, Jeong In Han, Dae Gyu Moon, Won Keun Kim, Min Gi Kwak, 2003). However, the mobilities of these devices are very low and the fabrication methods are not very practical and extensible to industry setup.